Method of preserving perishable material



Oct. 10, 1967 w. o. TUNDERMANN ET AL 3,346,398

METHOD OF PRESERVING PERISHABLE MATERIAL Filed Jan. 10, 1964 IN VENTORSw o. TUNDERMANN S.D. FRIEDMAN United States Patent Office 3,346,398Patented Oct. 10, 1967 3,346,398 METHOD OF PRESER G PERISHABLE MATERIALWerner O. Tundermann, Colonia, and Stuart D. Friedman, Bound Brook, NJ.,assignors to Colgate-Palmolive Company, New York, N.Y., a corporation ofDelaware Filed Jan. 10, 1964, Ser. No. 337,039 Claims. (Cl. 99--171) Thepresent invention relates to the preservation of perishable materialscontaining animal or vegetable matter which is subject to spoilagecaused by bacteria or molds. The invention is primarily concerned withthe preservation of such materials by maintaining them in a bactericidaland fungicidal atmosphere.

Extensive work has already been done on various methods and materials tobe used in preventing the spoilage of perishable organic matter. Onegeneral approach to this problem, extensively employed in the field offood preservation, has been to package the particular food commodity inan evacuated container. By the removal of air and moisture, theprocesses of deterioration are greatly retarded. Other methods involveheating the material to sterilizing temperatures prior to packing orstorage. Another approach to the problem, sometimes used in conjunctionwith the vacuum packing or heat sterilizing methods previously noted,has been to flood the container with a sterilizing agent prior toclosing of the package, so that a sterilizing atmosphere is maintaineduntil the package is opened;

In processes of the latter type, considerable attention has beendirected to the use of epoxides, such as ethylene oxide and propyleneoxide, as sterilizing agents. Although the epoxides have been found toexhibit excellent bactericidal and fungicidal activity, certain seriousdisadvantages have sharply limited their usefulness.

Among the more serious drawbacks involved in the use of epoxides assterilizing agents is the explosive character of epoxide-air mixtures.This problem presents a serious safety problem in large scale commercialpackaging processes employing such materials and makes the epoxidesgenerally unsuited to home use, i.e., use in packages which aredistributed directly to the consumer and are taken into the home, asopposed to bulk commercial packaging.

Another disadvantage in the use of the epoxides has been their tendencyto quickly volatilize and escape from the storage container. When sealedcontainers into which epoxide sterilizing agents have been introducedare opened, the epoxide vapors escape almost instantaneously. Theepoxide vapors also escape very rapidly from containers which are nothermetically sealed and they may even escape rapidly from many types ofsealed containers, since a number of conventional packaging materialsare readily permeated by the epoxide vapors.

In order to overcome this problem, attempts have been made to utilizethe epoxides in the form of solutions in solvents, such as carbondioxide, isopropyl formate and ethylene dichloride which tend to lowerthe vapor pressure of the epoxides. However, such epoxide solutions havenot been entirely successful due to cost, adulteration of the flavor,color or texture of foods contacted by the solutions, the production ofundesirable residues and the like. In addition, the lowering of thevapor pressure in solutions of this type is only suflicient ao enablethe epoxide to be handled as a liquid and introduced into the package.Thereafter, the epoxide vaporizes rapidly and is subject to the samedrawbacks noted in the previous paragraph.

As between ethylene oxide and propylene oxide, it has been found thatthe latter is generally more satisfactory as a sterilizing agent, for anumber of reasons. For example, upon reaction with Water or moisture inthe presence of food, propylene oxide hydrolyzes to form propyleneglycol which is substantially non-toxic when consumed in amounts of themagnitude that would be found on or in food packaged in an atmosphere ofpropylene oxide. On the other hand, ethylene oxide hydrolyzes to produceethylene glycol which is considerably more toxic. Also, while bothpropylene oxide and ethylene oxide are explosive when mixed with air,propylene oxide-air mixtures are explosive over a much narrower or morerestricted composition range than are mixtures of air and ethyleneoxide. Another important advantage of propylene oxide is that it is aliquid under normal conditions of temperature and pressure and thereforeis easier to handle than ethylene oxide which is normally a gas.

No entirely satisfactory method for using ethylene oxide as abactericide for organic matter is presently available. Notwithstandingthe advantages of propylene oxide over ethylene oxide, no fullysatisfactory method for safely and efficiently utilizing propylene oxideas a bactericide and fungicide for the preservation of foodstuffs andother animal and vegetable matter has as yet been developed. Especiallylacking has been a suitable method for utilizing ethylene oxide orpropylene oxide to sterilize packaged foods which are sold to theconsumer and which may not be sealed against the atmosphere or may beopened and reclosed a number of times before the contents of the packageare exhausted.

A satisfactory method for the use of ethylene oxide or propylene oxideas sterilizing agents in commercial bulk or retail scale packagingshould be convenient, economical and safe. Conventional methods haverequired special containers or filling apparatus which are bothcomplicated to use and are expensive. Other common techniques have usedthe epoxides in vapor form and introduce a considerable explosionhazard.

It is, therefore, an object of the present invention to provide safe,convenient and economical methods and compositions for employingethylene oxide and/or propylene oxide as sterilizing agents for organicmatter.

A further object of the invention is to provide methods and compositionsfor sterilizing organic matter by the use of ethylene oxide and/ orpropylene oxide which are safe, require no special receptacles and donot call for expensive or elaborate equipment to maintain specialconditions of temperature or pressure during their use.

A further object of the present invention is to provide a safe andefiicient method for using ethylene oxide and propylene oxide assterilizing agents without serious danger of explosion.

A further object of the present invention is to provide compositionscomprising ethylene oxide and/or propylene oxide and methods employingsuch compositions which enable animal and vegetable matter to bepreserved from spoilage safely and conveniently and over extendedperiods of time.

Another object of the invention is to provide a method and compositionsfor preserving food by maintaining the food in an atmosphere comprisingethylene oxide and/or propylene oxide vapors.

An additional object of the present invention is to provide a method andcomposition for packaging food, especially food for distribution toconsumers so that a sterilizing atmosphere of propylene oxide may bemaintained in the package over an extended period of time.

The manner in which the foregoing objects and many other highlydesirable objects are realized will be apparent in the light of thefollowing detailed description of the invention and by reference to theaccompanying drawings.

In the drawings:

FIG. 1 is a side cross-sectional view of a container including asterilizing .composition in accordance with the present invention;

FIG. 2 is a side cross-sectional view of a container comprising anothercomposition in accordance with the present invention;

FIG. 3 is a side cross-sectional view of a portion of a sheet ofpackaging material coated with a sterilizing composition of the presentinvention;

FIG. 4 is a side cross-sectional view of a portion of a sheet ofpackaging material comprising a sterilizing composition of the presentinvention; and 7 FIG. is a side cross-sectional view of a package madefrom the material of FIG. 3 or FIG. 4.

The present invention generally comprises the preservation of animal andvegetable matter from spoilage by exposing such materials to anatmosphere of ethylene oxide and/or propylene oxide vapors and byproviding for the relatively slow and controlled release of the ethyleneoxide and/or propylene oxide vapors into the atmosphere surrounding thematerial to be protected.

In accordance with the invention, compositions are provided which arecapable of slowly releasing or diffusing sterilizing ethylene oxideand/or propylene oxide vapors over extended periods of time so that thesterilizing atmosphere may be maintained and continuously regenerated incircumstances where the food or other materials is temporarily exposedto the atmosphere, where the container is not air tight or where thecontainer is constructed at least in part from materials pervious toair, moisture or propylene oxide vapors.

The invention also comprises compositions containing ethylene oxideand/or propylene oxide which are safe to use, which gradually releasesterilizing vapors and which are so economical that they are entirelydisposable.

According to one principal embodiment of the present invention, animalor vegetable matter which is to be preserved is placed in a containertogether with an amount of molecular sieve having absorbed thereinethylene oxide and/ or propylene oxide as a sterilizing agent. It hasbeen found that molecular sieves absorb moisture in preference toalkylene oxides so that as moisture is absorbed from the food or fromthe atmosphere surrounding the food or other organic matter in thecontainer, alkylene oxide is gradually released from the molecular sieveinto the atmosphere to maintain the contents in a sterilizing condition.The moisture, when absorbed in the sieve, results in desorption of theethylene oxide or propylene oxide. The moisture may be taken from thecontents of the container, such as a foodstufi, or from the atmospherepresent when the container is closed or admitted when the container istemporarily opened. Thus, not only does the molecular sieve function asa reservoir for the epoxide sterilizing agent, but it alsosimultaneously provides a dehydrating function which further contributesto the inhibition of mold growth and other processes of spoilage. I Theslow diffusion or exudation of ethylene oxide or propylene oxide vaporsfrom the molecular sieves has the added very important advantage thatdiffusion takes place more rapidly in high moisture containingatmospheres. Since it is under conditions of high relative humidity thatthe danger of spoilage is most acute, the fact that the release of thesterilizing agent takes place more rapidly under such conditions is anespecially important aspect of the invention. The release of absorbedsterilizing agents from other adsorbents would not ordinarily beresponsive to changes in relative humidity.

Another important embodiment of the present inven tion comprises theintroduction of ethylene oxide or propylene oxide liquid or gas intoclosed tubes, packets, capsules or the like which are pervious topropylene oxide vapors and the insertion of such epoxide containers intoa package or receptacle containing material to be preserved againstspoilage. This method enables the diffusion of the epoxide vapors to becontrolled so that the sterilizing agent is continuously but graduallydiffused through the wall of the capsule into the atmosphere surroundingthe food or similar material.

A preferred method for carrying out this embodiment of the inventioncomprises introducing liquid ethylene oxide and/or propylene oxide intoa sealed tube or capsule of a plastic which is permeable by the alkyleneoxide vapors. For example, polyethylene is a very suitable ma terial foruse in forming the capsules or tube to receive the sterilizing agent.

It will be understood that other materials capable of holding liquid orvaporized ethylene oxide and/ or propylene oxide and of diffusing theirvapors may also be used in place of the polyethylene. In addition, thewall thickness of the particular material and the rate at which itpermits propylene oxide vapors to pass may be selected so as to bestsuit the particular circumstances. Other filmforming materials throughwhich ethylene and propylene oxides Will diffuse and which are thereforeuseful in the present invention include ethyl cellulose, rubber hydrovchloride, cellulose acetate, cellulose nitrate and polypropylene.

Another very important embodiment of the invention comprises theincorporation of liquid propylene oxide into a fixative which enablesethylene oxide and/ or propylene oxide vapors to be slowly and graduallyexuded or diffused. The preferred method for accomplishing thisembodiment of the invention comprises dissolving propylene oxide in afilm-forming fixative. This solution may then be used as a coating orimpregnant on various materials used for the packaging of food orsimilar commodities. Examples of such fixatives are polyethylene glycolpolymers having molecular weights ranging from about 200 to about 600 orhigher, cellulose acetate, cellulose nitrate, shellac, etc.

Although the incorporation of ethylene or propylene oxide in capsulespermeable to their vapors or in fixative coatings does not have theself-regulatory feature of molecular sieves containing absorbed oxides,their slow but constant release of the oxide acts effectively over aperiod of time and they avoid the need for using high temperatures orlow pressures and are much safer to handle than prior compositions andmethods.

The use of molecular sieves containing absorbed propylene oxide tosterilize foodstuffs or the like is illustrated in FIG. 1 of thedrawing. As will be seen by reference to this figure, container 10 isfilled with a material 11 which is to be preserved against spoilage. Oneor more pellets of molecular sieve 12 containing absorbed ethylene oxideor propylene oxide are introduced into the container to furnish thedesired sterilizing atmosphere.

It will be understood that the contents 11 of the container 10 may beany material of animal or vegetable origin which may be attacked bybacteria or mold. Likewise, the container 10 may be of any size andconstruction. For example, it may be the familiar small volume metal canor jar employed in sales to the consumer and having a volume of from afew ounces up to one or two quarts. On the other hand, the container maybe a drum of considerable capacity used in commercial operations andhaving a volume of many gallons. Similarly, the container may beconstructed of metal, plastic, paper and combinations of these and otherconventional packaging materials.

If desired, the molecular sieve pellets 12 may be segregated from thecontents 11 of the container by a perforated diaphragm 13 which freelypermits transfer of moisture and the ethylene oxide or propylene oxidevapors between the molecular sieve compartment 14 and the othercompartment 15 in which material subject to spoilage is located.

Where the contents of the container to be preserved are materials forinternal human or animal consumption,

propylene oxide is used as the sterilizing agent since its residue issubstantially non-toxic. Otherwise, ethylene and/ or propylene oxide maybe used.

It will also be understood that the amount of molecular sieve andalkylene oxide composition may be varied in accordance with the size ofthe container and its intended or usual method of use. For example, ifthe container is the type which is sealed air tight and then isordinarily opened, emptied, and disposed of, then only enough of thesterilizing composition need be included to maintain sterility withinthe container prior to opening. However, if the container is of a typewhich is ordinarily opened, partially emptied and reclosed, more of themolecular sieve-propylene oxide composition may be desirable, so thatthe sterilizing atmosphere may be regenerated a number of times as thecontainer is opened and reclosed.

Molecular sieves of the type used in this invention are crystallinemetal aluminosilicate materials of the following general formula:

Mg o YA1203 in the salt form, where n is the valence of the metal cationM, M ordinarily is Na or K but may be other cations substituted byexchange, Y is the number of moles of alumina and Z is the number ofmoles of Water of hydration.

Upon removal of the water of hydration by heating, the crystalline metalaluminosilicates become highly porous and are characterized by a seriesof surface cavities and internal pores which form an interconnectingnetwork of passageways within the crystal. Due to the crystalline natureof such materials, the diameters of the surface cavities and of theinternal pores is substantially constant and is of molecular magnitude.For this reason, the crystalline metal aluminosilicates have found wideuse in the separation of materials according to molecular size orconfiguration, hence the name molecular sieves.

Molecular sieves or crystalline aluminosilicates are also sometimesreferred to as crystalline zeolites and are of bot-h natural andsynthetic origin. Synthetic materials include, for example, syntheticfaujasite. Natural crystalline aluminosilicates exhibiting molecularsieve activity include for example, analcite, paulingite, ptilolite,clinoptilolite, ferrierite, chabazite, gmelinite, levynite, erionite andmordenite.

Since not all of the natural crystalline aluminosilicates are availablein abundance, considerable attention has been directed'to the productionof synthetic equivalents. A number of these are available on acommercial scale and are designated as X molecular sieve, Y molecularsieve, and A molecular sieve. Other molecular sieves which have beensynthesized include B, F, G, H, K-G, I, L, M, K-M, Q, R, S, T, U and Zzeolites.

While it is contemplated that any molecular sieve which absorbs waterwith preference to ethylene oxide or propylene oxide will be suitableforuse in accordance with the present invention, it has been found that theLinde 13X molecular sieve is especially satisfactory. The synthesis andcomposition of the X molecular sieves are described in US. Patent No.2,882,244, Milton, issued Apr. 14, 1959. Y molecular sieve is describedin Belgian Patent 577,642, and A molecular sieve is described in U.S.2,882,243, Milton and 2,982,612, Barrer et al.

The numerical prefix in the designation or identification of variousmolecular sieves indicates the approximate pore size in angstroms. Forexample, 13X molecular sieve is a sieve of the X type which is believedto have pores having diameters of about 13 angstroms. On the other hand,a A molecular sieve is a synthetic crystalline aluminosilicate of the Atype having pores the diameters of which are approximately 5 angstroms.

In accordance with the present invention, sterilizing compositions areprepared by heating a molecular sieve material, preferably in the formof compacted pellets, spheres or the like to remove moisture and thencausing Sliced Tomatoes.--

6 the dried sieve to be impregnated with ethylene oxide or propyleneoxide. The impregnation may be accomplished by immersing crystals orpelleted crystals of the molecular sieve in liquid ethylene oxide orpropylene oxide or by placing the pellets or crystals in a closed vesselcontaining the oxide vapors.

As an example of the later method, 123 tablets of 13X molecular sievehaving a thickness of A and a diameter of were baked overnight in anoven at a temperature of 500 F. to drive off absorbed moisture. Thedried tablets were then quickly transferred to a porous bag and the bagwas suspended in a closed glass container above the level of liquidpropylene oxide placed in the bottom of the container. The molecularsieve was thus exposed for a period of 5 days during which time thetemperature was maintained at about 45 F. Upon Weighing, it was foundthat the molecular sieve had adsorbed about 20% by weight of propyleneoxide into its pores.

As demonstrated in the following examples, the molecular sieve-propyleneoxide composition is quite effective in preventing or reducing thespoilage of various foodstuffs.

Examples 1-3 Grams Bag No. 2 1.6 Bag No. 3 3.2

After four days, the pumpkin meat in Bag No. 1 was observed to becovered with heavy black fungus. The

pumpkin meat in Bag No. 2 showed some softening and the presence of aconsiderable amount of liquid, but the fungus growth was not asextensive as in Bag No. l. The pumpkin meat in Bag No. 3 was in goodcondition.

Example 4 Sliced fresh tomatoes were placed in two glass jars. In one ofthe jars was placed one tablet of a 13X molecular sieve saturated withabout 20% by weight of propylene oxide. The tablet was A" in diameterand A" thick. Both jars were then sealed.

Example 5 The same procedure was then followed with sliced bologna.

Example 6 The procedure was then followed with pieces of cheese cake.

After one Week, observation of the food in the jars showed the followingresults:

Protected by Molecular Control Sieve Propylene Oxide Slices covered withwhite N o evidence of fungus. fungus.

Sliced Bo1ogna. Slices showed spots of D0.

both White and black fungus.

Cheese Cake Cake showed several Do.

spots of blue fungus.

It will be seen from the above examples that the incorporation ofmolecular sieve material saturated with propylene oxide into foodpackages greatly extends the materials may be protected from spoilage.When other forms of propylene oxide sterilizing gas are incorporatedinto food containers, such as liquid propylene oxide, solutions ofpropylene oxide or the like, the gas volatilizes quite rapidly and issubstantially lost almost immediately upon opening of the 'packageorexposure of the propylene oxide to the atmos- "phere. According to thepresent invention, however, it

A slice of bread and two drops of water were placed in a polyethylenebag and the bag was folded closed. A second slice ofbread, two drops ofwater and a tube of polyethylene containing cc. of propylene oxide werethen placed in a second polyethylene bag which was likewise foldedclosed.

After twelve days, it' was observed that fungus growth had begun on theslice placed in the first bag, but that no fungus growth had commencedon the slice of bread .placed in the bag with the polyethylene tubecontaining propylene oxide. Upon observation after several months, nofungus growth was found to have commenced on the slice of bread in thebag containing the tube of propylene oxide.

Example 8 p A slice of bread inoculated with a penicillin'fungus wasplaced in a first polyethylene bag and the bag was folded closed. Asecond slice of bread inoculated with the same amount and type ofpenicillin fungus as the first slice was placed in a second polyethylenebag with a polyethylene tube containing 12 cc. of propylene oxide. Thebag was then folded closed.

After five days, extensive mold was observed on the slice of breadplaced in the first bag. The slice of bread placed in the second bagwith the tube of propylene oxide was free from mold. Again, as inExample 7, observation after the elapse of several months showed no moldto be present on the slice of bread in the second bag.

According to the second major embodiment of the invention, asillustrated in FIG. 2 of the drawing, food 21 and a tube 22 containingethylene oxide and/ or propylene oxide 23 are placed into anoutercontainer 24 and the container is then closed The tube preferably ispolyethylene or other plastic which is pervious to the alkylene oxidevapors and which enables the vapors to dififuse through the wall of thetube into the atmosphere surrounding the food 21.

Tube 22 may be dropped into the container with the food or may beadhesively attached to the bottom of container 24 or to its side wallsor may be placed in a pocket, clamp or recess in a wall of the containeror in the closure. As one alternativeto this embodiment, the plasticused to form the tube may be of a Water soluble or disintegrable natureand may be edible as well, so that if the food -placed in the containercontains substantial amounts of water, the tube will disintegrate afterrelease of the propylene oxide and will leave no undesirable residue.

The third major embodiment of the present invention, as previouslydescribed, generally comprises dissolving or dispersing ethylene oxideand/or propylene oxide in a fixative which gradually releases propyleneoxide vapors to the atmosphere. The fixative is preferably afilm-forming substance which can be used to coat or impregnate packagingmaterials. If at least part of an interior wall of a package made fromsuch material carries such a coating, propylene oxide vapors willgradually be released to v the atmosphere within the package.

As illustrated in FIG. 3 of the drawing, a specific example of materialprepared in accordance with this invention may comprise a conventionalpaper-foil laminate of the type widely used for packaging foods. Thelaminate comprises a layer of paper 31 adhesively bonded to a foil ofaluminum 32 or other impermeable material. The other surface of thepaper is coated with a film 33 of a fixative containing propylene oxide.The film 33 may, for example, comprise -a concentrated solution ofethylene oxide and/ or propylene oxide in a polyethylene glycol polymerhaving a molecular weight of about 200.

As a modification of this general embodiment, the filmforming fixativesolution containing ethylene oxide and/ or propylene oxide may beapplied as an interlayer between an impermeable foil and a vaporpermeable layer.

Referring to FIG. 4 of the drawing, the laminated sheet material shownin cross-section comprises a vapor permeable layer 41, such aspolyethylene, cellulose acetate or the like, a vapor impermeable layer43, such as aluminum foil or heavy waxed paper, and an interlayer 42which is a film of fixative containing ethylene or propylene oxide. Asthe sterilizing agent is gradually released from the fixative film, suchas cellulose nitrate, it diffuses through the permeable layer 41.

As further illustrated in FIG. 5, materials of the type shown in FIGS. 3and 4 may be used to form a package 51 for foods 52, such as slicedmeats, cheeses, or the like by wrapping the material around the articleto be packaged and crimp sealing as at 53. In each case, the material isemployed so that the impermeable foil layer 32 or 43 is on the outsideso that the propylene oxide vapors may difiuse and fill the inside ofthe package 51.

Other methods for forming and sealing packages made from materialscoated or impregnated with the fixativepropylene oxide composition willbe readily apparent.

It will also be seen that the relative amounts of fixative and propyleneoxide or ethylene oxide in the present compositions may be varied andthat the compositions may be applied to a great variety of packagingmaterials with the same beneficial results. For example, any rigid orflexible packaging or wrapping material, whether of paper, cardboard,wood, plastic, or metal, or of either single ply or laminatedconstruction, may be coated over part or all of one or both surfaces sothat in packages or containers formed from the material, the ethyleneoxide or propylene oxide sterilizing agent in the fixative is releasedwithin the container. I

While the present invention has been fully described and illustratedwith reference to certain preferred embodiments, it will be apparent tothose skilled in the art that various modifications may be made withoutdeparting from the spirit of the invention or the scope of the followingclaims.

What is claimed is:

1. A method for the preservation of perishable material which comprisesplacing in a container which is impermeable to air animal or vegetablematter subject to spoilage by bacteria or molds and a sterilizingcomposition comprising a crystalline porous metal aluminosilic-ate andan alkylene oxide selected from the group consisting of ethylene oxideand propylene oxide absorbed within the pores of said aluminosilicate,closing said container using an airtight sealing means and maintainingsaid matter in a sterilizing atmosphere of said alkylene oxide vaporsforan extended period of time by the slow and controlled release of'saidvapors from said sterilizing composition into the atmosphere surroundingthe matter to be protected in response to changes in relative humiditywithin said container.

2. A method in accordance with claim 1 wherein said aluminosilicate is asynthetic molecular sieve.

3. A method in accordance with claim lwherein said sterilizingcomposition is segregated from said matter subor animal consumption andsaid sterilizing composition is propylene oxide absorbed in saidaluminosilicate.

5. A method for the preservation of perishable material which comprisesplacing in a glass container animal or vegetable foodstufis for humanconsumption which are subject to spoilage by bacteria or molds and aporous crystalline aluminosilicate 13X molecular sieve having propyleneoxide absorbed within its pores in an amount of about 20% by weight ofsaid sieve, sealing said glass container using an airtight sealing meansand maintaining said foodstuffs in a sterilizing atmosphere of saidpropylene oxide vapors for an extended period of time by the slow andcontrolled release of said vapors from said propylene oxide-containingmolecular sieve int-o the atmosphere sur- 15 rounding the foodstufis tobe protected in response to changes in relative humidity within saidcontainer.

References Cited UNITED STATES PATENTS 1,765,920 6/1930 Humpert.

2,370,768 3/1945 Baerwald 99171 2,979,410 4/ 1961 Parlour 991713,033,642 5/1962 Bukata 23-112 X 3,062,659 11/1962 Hyson et al.

3,183,057 5/1965 Mark-s et a1. 2158 3,234,028 2/1966 Dunham et al.99-l50 X OTHER REFERENCES Chemical Loaded Molecular Sieves, Aug. 3,1959, published by Linde Company, Division of Union Carbide Corporation,pp. 1 to 6, inclusive.

HYMAN LORD, Primary Examiner. A. LOUIS MONACELL, Examiner.

1. A METHOD FOR THE PRESERVATION OF PERISHABLE MATERIAL WHICH COMPRISES PLACING IN A CONTAINER WHICH IS IMPERMEABLE TO AIR ANIMAL OR VEGETABLE MATTER SUBJECT TO SPOILAGE BY BACTERIA OR MOLDS AND A STERILIZING COMPOSITION COMPRISING A CRYSTALLINE POROUS METAL ALUMINOSILICATE AND AN ALKYLENE OXIDE SELECTED FROM THE GROUP CONSISTING OF ETHYLENE OXIDE AND PROPYLENE OXIDE ABSORBED WITHIN THE PORES OF SAID ALUMINOSILICATE, CLOSING SAID CONTAINER USING AN AIRTIGHT SEALING MEANS AND MAINTAINING SAID MATTER IN 